Method of manufacture of molecular sieves

A method of producing a material comprising the steps:

• (a) contacting at least one synthetic zeolite selected from the group consisting of structure types FAU, EMT, LTA, CHA, MOR, OFF, ERI, zeolite ZK-5, BEA, GME and combinations thereof and containing sodium ions, potassium ions or mixtures thereof with a source of trivalent cations, thereby replacing most of the sodium ions, potassium ions or mixtures thereof with trivalent cations and producing trivalent cation-exchanged zeolite;
• (b) calcining the trivalent cation-exchanged zeolite at a temperature in the range of about 200 to about 650° C.;
• thereby generating protons as exchangeable cations, then contacting the calcined zeolite with a water-soluble potassium salt;
• and
• (c) contacting the calcined zeolite with a source of sodium, lithium, rubidium, cesium, magnesium, calcium, strontium, silver and/or first row transition metal cations or mixtures thereof in a reaction zone, thereby replacing protons and at least some of the initial cations remaining on the zeolite with sodium, lithium, rubidium, cesium, magnesium, calcium, strontium, silver and/or first row transition metal cations, or mixtures thereof.